The invention relates to a rotary actuator, particularly for controlling a throttle cross-section in a line carrying operating fluid for an internal combustion engine.
An electromagnetic rotary actuator is known comprising an actuating motor with a stator which is fixed with respect to a housing cap in which the motor is located and with a rotatable rotor which is mounted on a rotor shaft nonrotatably attached to a throttle member which more or less opens a control opening.
Such rotary actuator is already known from German Offenlegungsschrift 37 28 589 but the rotary slide valve of this actuator is supported to be rotatable about a shaft carried in two housing parts. The sealing between the pneumatic part and the electrical part is there effected by the throttle member covering the control opening in the pneumatic housing, which, however, may not "come into grazing contact" in spite of the tolerances required. If dirt particles, shavings or water droplets carried by inadequately cleaned combustion air pass through the sealing gap into the electrical part of the rotary actuator, functional disturbances or corrosion can occur. In addition, air can be sucked away from the electrical part in an unwanted manner and erroneously change the desired fuel/air ratio.